Legally you have to have both plates on your car in CA. One in the front and one in the back.
But...many NSX and exotic cars do not put them on the front. The worst that can happen is that a cop pulls you over for not having a front license plate. He smells marijuana coming from the car. He asks to inspect the car and he finds a kilo of cocaine. He throws you in jail and now you are facing hard time for intent to distribute.
Or the other scenerio is that he writes you a fix-it ticket. You put your front license plate on with zip ties, pay your $10-$15, and find a cop to write it off. As soon as he writes it off, you cut the zip ties and the game starts over again.
To get another license plate, you can go to the DMV or AAA (for members). At AAA office they have license plates there and you will pay a small fee $10-$20. You surrender your old license plate and they give you a new license plate and stickers there on the spot.